1. Department of General Surgery, Hillingdon Hospital, The Hillingdon Hospitals NHS Foundation Trust , London, UK
2. MRC Clinical Trials Unit at UCL, Institute of Clinical Trials and Methodology, University College London , London, UK
3. Department of General Surgery, Royal Victoria Hospital , Belfast, UK
4. Department of Thoracic Surgery, Guy’s and St Thomas’ NHS Foundation Trust , London, UK
5. Department of Thoracic Surgery, University College London Hospitals , London, UK